Model-based prediction of maximum pool size in the ribbon synapse
© Parmelee et al. 2015
Published: 18 December 2015
Maximum pool size predictions from pulse train data
Estimate for A, from back-extrapolation
Estimate for A, from the model
-10 mV (stronger)
-30 mV (weaker)
We developed a model-based approach to estimate A from the limiting release R. We modeled the rate of release (resp. replenishment) to simply be proportional to the number of vesicles on the ribbon (resp. vacant ribbon sites), and using the measured timescale τr (resp. τa). By solving the alternating differential equations, we derived a recurrence relation for the release during each pulse, Ri, which we then solved to obtain a closed form expression for Ri and the limiting release R. Specifically, we found that A = cR, where c is a function of τr,τa,Δt,T, and p, with p a release constant that captures the stimulus dependence of release probabilities, and can be estimated from the first release, R1. In contrast to the back-extrapolation method, our model-based estimate for A was similar across stimulus types (Table 1), while p was much smaller for the weaker stimulus. This suggests that available pool size does not change with stimulus strength; instead, differences in release result from changes in release probability.
- Sakaba T, Schneggenburger R, Neher E: Estimation of quantal parameters at the calyx of Held synapse. Neurosci Res. 2002, 44 (4): 343-356.PubMedView ArticleGoogle Scholar
- Van Hook MJ, Parmelee CM, Chen M, Cork KM, Curto C, Thoreson WB: Calmodulin enhances ribbon replenishment and shapes filtering of synaptic transmission by cone photoreceptors. J Gen Physiol. 2014, 144 (5): 357-378.PubMedPubMed CentralView ArticleGoogle Scholar
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.